Hi Astro14.
You guys actually got paid to do this
I notice it is a 'hands off' take off. Looking at that vid from 1:06 i noticed the tail surfaces moving. Is this to give lift? Also if the pilot is hands off does the aircraft computer take care of the initial launch?
Thanks
Tikka.
I honestly couldn't imaging doing that.
One of my friends was some kind of Flight controller on an aircraft Carrier during the Vietnam war and got a ride on an A4 he loved it and my neighbor an A4 pilot during the same time era said is was the best thing on Earth and I am sure Astro14 knows the words of the description but I will get banned if I post the description. We make heros out of race car drivers but the pilots are so much "mo betta".I would love to be in the back seat. I think Tom Cruise did some of these filming Top Gun 2.
Hi Astro14.
You guys actually got paid to do this
I notice it is a 'hands off' take off. Looking at that vid from 1:06 i noticed the tail surfaces moving. Is this to give lift? Also if the pilot is hands off does the aircraft computer take care of the initial launch?
Thanks
Tikka.
Hi Astro14.
An outstanding explanation as always. Thank you.
Of course! The hands off guy at 1:06 is a back seater. I thought he was the pilot and the computer was taking the aircraft from the carrier. Doh!
There was much debate over here during the design stage of the Queen Elizabeth carriers about whether a catapult system was to be used or not. Ultimately the costs involved with the EMAL system led them to use the ski jump and F35B.
From a layman's point of view i think they should have found the extra cash. Too many compromises made.
Yeah...we got paid to do that...and I loved it.
So, to answer what’s going on in the video you see, let’s first talk about the cat shot. EMALS is the new technology, electromagnetic induction to provide the force to accelerate an airplane from dead stop to about 170 knots in a space just under 100 meters. Steam is the old, and still prevalent, technology.
The catapult (as opposed to ski jumps, or VTOL) allows the use of heavier and higher performance airplanes. It also requires less free flight deck space than a ski jump and more launch capability in a given window.
The catapults as installed on a USN carrier accelerate the airplane to flying speed by connecting a shuttle (which is a fitting connected to the motive force, steam tubes, induction motor, etc. below the deck) to the airplane. On very old airplanes like the F-4 and F-8, a cable known as a bridle was used. Current airplanes all have a launch bar, that is a steel bar, connected to the nose gear, that engages the shuttle. The launch bar is normally retracted.
When the launch bar is hooked into the shuttle, all slack has to be removed, or the shock load from the cat firing would break the bar and the airplane*. So, a second fitting is used, called a “hold back” and the holdback does just that: hold the airplane back against full engine power. This allows the shuttle to securely engage the launch bar, and the engines to be placed at full power, so that everything is ready when the cat is fired.
The catapult officer does a set of calculations based on aircraft type, weight, wind, temperature, and available steam/energy. The impulse is calculated to provide enough energy to get that airplane launched with that set of conditions. On a windy day, say, when the carrier is making 25-30 knots of wind, and when the airplane is light, say, in the case of a Tomcat at 54,000 lbs, the cat shot is sweet, about 2G acceleration (makes a Tesla in ludicrous mode look slow).
But with light wind, hot day (air density lower, so more speed is needed) and a heavy airplane, say, a 69,000# Tomcat loaded for combat, the cat shot can be brutal. Over 3G acceleration (perhaps more than 4G, as I did some math...) to achieve that flying speed in under two seconds. It's also brutal because the nose strut extends at the end of the stroke and there is a big change in the rate of acceleration (third derivative of position with respect to time, known as "jerk"). Makes for quite a jolt on a heavy shot.
The basic sequence (no arming of weapons) -
The airplane is guided into the catapult by the yellow shirt (taxi director). Yep, they’re so good that the airplane is within the 1/2” needed to be aligned with the shuttle. The airplane unfolds/spreads wings and the blast deflector is raised (a big shield behind the airplane to protect everyone/thing from the jet exhaust). The launch bar is lowered and the airplane taxied into the shuttle. The holdback is connected, shuttle engaged and the signal is given to “take tension” - where slight forward pressure is applied to the shuttle. When in tension, the pilot runs the engines up to full power, AB if needed, and moves the flight controls through their full range, checking instruments and controls. Safety observers from that squadron observe the controls, and check for leaks/problems, they give a thumbs up. When the pilot is satisfied with the control feel, instruments and airplane, they salute the cat officer. Cat officer checks the troubleshooters, forward of the track, and fires the cat.
Airplane goes zero to 170 in two seconds. Awesome.
* The load on the airplane is incredible. The launch bar is about the size of my forearm. In the case of the F-14, the nose strut is compressed (we called it kneeling) for launch and over 200,000 lbs of load goes through that bar into the airframe to accelerate the jet.
It doesn’t always work out. A friend of mine, LCDR Chris “Basher” Blaschum, had the nose strut come apart during a cat shot many years ago. Corrosion internal to the strut weakened its ability to handle that load and it failed. He tried to save the airplane by going into AB and flying it, but there wasn’t enough speed or time. The RIO ejected, and made it. Basher didn’t.
RIP Basher, my friend, until Valhalla.
I was actually at war college in Shrivenham (Joint Services Command and Staff College) when the RN was debating the carrier configuration.
Here was the thinking:
The entire F-35 was experiencing delays. So was EMALS. If the RAF (and politicians) sensed weakness on the ability of the RN to get the carrier program operational on time, there was a very real chance it would be cut.
By ditching EMALS you lost the risk of delays in that program. Further, if you went with a ski jump, you could use Harrier GR.9, borrowed from the RAF, to fill the carrier air wing, so you lose the risk of the F-35 program delays. The carrier would be operational on time, with or without EMALS and with or without the F-35.
Ultimately, the F-35B is a lower performance airplane than the F-35C that the RN really wanted, but they wanted to ensure the political survivability of the carrier program, so they made the big change.
RIP LCDR.
Would you say the explanation you gave here is what is shown in the opening credits of Top Gun?
You can see them doing various things, Including hauling fuel lines, but some of it is cinching up the front of the plane, raising the blast shields, etc.
From approximately 1:15
Say what anyone might about the movie, that opening footage with the radio chatter and the aircraft activities is some of my favorite footage of any movie ever.
Hi Astro14
Once again thank you for replying.
I see what you mean about the politics and inter service rivalry. Good points.
The RAF are now pushing for F35A instead of the whole order being F35B and 'shared' with the navy. I realise my knowledge is only veneer thin but i really hope the F35 is the aircraft that it professes to be and not a very expensive white elephant.
Do you think fitting the Elizabeth class carriers with steam catapult was a viable option? I am concerned about lack of aircraft types severely limiting future operations. The AEW for example will be fulfilled by Sea King Helicopter. No provision for electronic warfare aircraft other than the F35B own ability. This is fine if the carriers will be working as part of a NATO fleet but history has shown (Falklands) that this is not always the case.
The carriers can't even defend themselves having only CIWS armament.
I hope my Country looked after you on your visits.
Next time you get a few days in London with your airline, try to get up to the Imperial War Museum at Duxford near Cambridge. You will enjoy it.
I flew the T-34C, T-2C, and TA-4J in training before flying the F-14. Took longer back then...